1. Field of the Invention
The present invention relates to a single scale U-type manometer, particularly for use in measuring the height of liquids of different densities held in containers such as ballast-tanks or storage tanks, comprising a calibrated measuring tube, a reservoir for the manometric liquid communicating with said measuring tube, a connection with the enclosure which contains the liquid to be measured and a graduated scale.
It is known that elongation of the manometric liquid depends on the pressure being measured and on the density of the manometric liquid.
It is likewise known that the pressure corresponding to a liquid height depends on the density thereof.
Consequently, the reading on the pressure scale depends on the density of the liquid whose height is to be measured and on the density of the manometric liquid. It follows then, that when the height of liquids differing in density is to be measured with a U-type manometer, it is necessary to vary the size of the manometric scale so as to obtain different graduations for each liquid, which is very often the case when the height of fuels or liquid gases stocked in tanks is to be measured.
2. Description of the Prior Art
The possibilities known at present for varying the size of the manometric scale is to operate on the scale itself. Thus, a so-called "elastic" manometric scale is used which gives very unsatisfactory mesuring results because of its lack of accuracy.
Also used for this purpose are pivotably mounted multiple scales in the form of a pivotably and slidably mounted chart but this type of scale, apart from the difficulties that its manufacture presents, is rather inaccurate, taking into account the fact that the graduation of each scale of the multiple scale introduces a certain measuring error.